Answer: HgNO₃
Explanation:
The empirical formula is the formula that shows the ratio of the atoms in its simplest form, this is using the smallest whole numbers.
The empirical formula may or may not be the same molecular formula.
In this case you are given the molecular formula Hg₂(NO₃)₂. Since, the ratio of the atoms of Hg, N, and O is 2: 2: 6, respectively, the same ratio is expressed if you divide by the greatest common factor (GCF).
The GCF of 2, 2, and 6 is 2. So, the ratios can be simplified to 1:1:3, meaning 1 mol of Hg, 1 mol of N, and 3 mol of O or HgNO₃.
